Detonation-induced coal gasification

A preliminary experimental and theorotical investigation of the feasibility of detonation-induced pulverized coal gasification is described. The concept envisions a closed annular detonation duct through which a hydrogen/oxygen gasphase detonation propagates continuously. Coal particles injected into the violent and rapidly changing atmosphere produced by the detonation would undergo gasification reactions and be subsequently expelled from the duct. These events would occur in a time period compatible with one revolution of the detonation. A one-dimensional analysis of the response of a single coal particle within the expansion-wave region behind the detonation front is presented. Independent variables include particle diameter, initial H₂/O₂ stoichiometry and expansion wavelength (at the time the particle is overtaken by the detonation front). The most significant result of this analysis is the prediction of relative gas/particle velocities ranging between 125 and 1500m/s, which are sustained throughout particle residence times of 1–15 ms corresponding to 10–1000 μm diameter particles. An experimental facility comprising a 47 m ‘single-shot’ detonation duct that was built for this study is discussed. The duct was 2.54 cm square and was terminated at each end by a 0.36 m diameter × 2.44 m long cylindrical tank which contained helium gas during a test. Sized coal particles were placed at a point within the first 3.7 m length of the duct, and thin brass diaphragms initially separated the duct from the two helium-filled tanks. Detonation was initiated at the duct, end closest to these particles. The diaphragm at that end burst, allowing combustion and gasification products to exhaust into the adjoining tank where they were quenched and decelerated. When the detonation reached the far end of the duct the second diaphragm burst, minimizing wave reflections which would otherwise return to the ‘test section’ end and interfere with the flow field there. After a test the contents of both tanks and the duct were circulated and mixed. A gas sample was then drawn and analysed for yield. Results from preliminary experiments using this facility are presented. Although too few tests were conducted for conclusive observations to be reported, in two experiments yields of CO + CH₄ representing 40 per cent of the total initial carbon content in the coal samples were obtained.     

传爆管用聚奥99炸药研究

介绍了具有高煤轰感度和耐热特性的聚奥99炸药的配方、制备工艺、性能以及装入传爆管后产品的性能和应用状况。     

可导通非电起爆系统研究

阐述采用非电导爆管组装成全封闭系统，以实现网路导通检查，并有效控制瓦斯引爆。     

Numerical simulation of detonation using an adaptive Cartesian cut-cell method combined with a cell-merging technique

A second-order accurate scheme for the Cartesian cut-cell method developed previously by the authors [Ji H, Lien F-S, Yee E. Comput. Methods Appl. Mech. Eng. 198 (2008), 432] is generalized for application to both two- and three-dimensional inviscid compressible flow problems. A cell-merging approach is used to address the so-called “small cell” problem that has plagued Cartesian cut-cell methods. In the present cell-merging approach, the conservative variables are stored at the cut-cell centroid (including the non-merged and merged cut-cells) rather than at the Cartesian cell center. Although this approach results in a more complicated search algorithm for the determination of the neighbor cells (required for the computation of the spatial gradients of the conservative variables), this approach enables the straightforward formulation of a higher than first-order accurate discretization scheme in the vicinity of the (complex and irregular) internal boundaries of the flow domain. Six test cases (including detonation problems) are used to demonstrate the accuracy and capability of the adaptive cut-cell method, for which both mesh refinement and derefinement techniques are employed in the case of an unsteady shock diffraction problem.     

Detonation propagation in narrow gaps with various configurations

In general all detonation waves have cellular structure formed by the trajectory of the triple points.This paperaims to investigate experimentally the propagation of detonation in narrow gaps for hydrogen-oxygen-argonmixtures in terms of various gap heights and gap widths.The gap of total length 1500 mm was constructed bythree pair of stainless plates,each of them was 500 mm in length,which were inserted in a detonation tube.Thegap heights were varied from 1.2 mm to 3.0 mm while the gap widths were varied from 10 mm to 40 mm.Variousargon dilution rates were tested in the present experiments to change the size of cellular structure.Attempts havebeen made by means of reaction front velocity,shock front velocity,and smoked foil to record variations of cel-lular structure inside the gaps.A combination probe composed of a pressure and an ion probe detected the arrivalof the shock and the reaction front individually at one measurement point.Experimental results show that thenumber of the triple points contained in detonation front decreases with decrease in the gap heights and gapwidths,which lead to larger cellular structures.For mixtures with low detonability,cell size is affected by a cer-tain gap width although conversely cell size is almost independent of gap width.From the present result it wasfound that detonation propagation inside the gaps is strongly governed by the gap height and effects of gap widthis dependent on detonability of mixtures.     

多相爆轰管的优化设计及其制备纳米氧化钛材料的探索研究

以三种前驱气体(CH4-2O2、H2-0.5O2、C2H2-2.5O2)进行爆轰试验,研究了初始压力对爆轰参数的影响及规律,以测得的预混气爆轰压力、速度、胞格等性能参数表征了预混气爆轰特性。以测得的爆轰参数为依据自主设计了长度2m、内径80mm、壁厚8mm、点火能量为40J的爆轰管道。在自主设计的爆轰管道内采用氢气、氧气和四氯化钛为混合前驱体,通过气液爆轰法合成了纳米二氧化钛,采用TEM对产物进行了表征,结果表明获得的纳米二氧化钛其球形或者类球形颗粒大约为20-150nm。     

Initiation Pressure Thresholds from Three Sources

Pressure thresholds are minimum pressures needed to start explosive initiation that ends in detonation. We obtain pressure thresholds from three sources. Run‐to‐detonation times are the poorest source but the fitting of a function gives rough results. Flyer‐induced initiation gives the best results because the initial conditions are the best known. However, very thick flyers are needed to give the lowest, asymptotic pressure thresholds used in modern models and this kind of data is rarely available. Gap test data are in much larger supply but the various test sizes and materials are confusing. We find that explosive pressures are almost the same if the distance in the gap test spacers are in units of donor explosive radius. Calculated half‐width time pulses in the spacers may be used to create a pressure‐time curve similar to that of the flyers. The very‐large Eglin gap tests give asymptotic thresholds comparable to extrapolated flyer results. The three sources are assembled into a much‐expanded set of near‐asymptotic pressure thresholds. These thresholds vary greatly with density: for TATB/LX‐17/PBX 9502, we find values of 4.9 and 8.7 GPa at 1.80 and 1.90 g/cm³, respectively.     

钝感猛炸药金属导爆索安全性试验研究

研究了作为爆轰传递与延期主体的小直径钝感猛炸药金属导爆索 ,在生产、使用、贮存与应用等环节中所涉及的诸如燃烧、烤爆、殉爆、弯曲、拉伸、撞击等作用后的安全可靠性。试验证明 ,外径为 0 .85mm,药芯直径约为 0 .45mm,装药量 0 .45g/ m的含有 HNS炸药的金属导爆索具有较高的安全性能。     

运用神经网络预测炸药爆速

本文计算了30个炸药分子的氧平衡(OB)、装药密度(ρ)、碳原子浓度nC/Vm、氢原子浓度nH/ Vm、氧原子浓度nO/ Vm、氮原子浓度nN/ Vm 6种参数,以这6种参数作为炸药分子结构描述符,构建人工神经网络模型,预测炸药爆速.预测结果表明,预测值和文献值的最大相对误差为5.35%,最小为0.53%,说明神经网络所确定的定量关系可以很好地用来预测炸药爆速.     

Detonation Failure Characterization of Homemade Explosives

Typically characterizing home made explosives (HMEs) requires many large scale experiments, which is prohibitive given the large number of materials in use. A small scale experiment was developed to characterize HMEs such as ammonium nitrate‐fuel oil mixtures. A microwave interferometer is applied to small scale confined transient experiments, yielding time resolved characterization of a failing detonation that is initiated with an ideal explosive booster charge. Experiments were performed with ammonium nitrate and two fuel compositions (diesel fuel and mineral oil). It was observed that the failure dynamics were influenced by factors such as the chemical composition, confiner thickness, and applied shock wave strength. Thin steel walled confiners with 0.71 mm wall thickness experienced detonation failure and decoupling of the shock wave from the reaction zone. Confiners with a wall thickness of 34.9 mm showed a decrease in propagation speed and a steady reactive wave was achieved. Varying the applied shock strength by using an attenuator showed corresponding changes in the initial overdriven reactive wave velocity in the HMEs. The distance to detonation failure was also shown to depend on the attenuator length when thin wall confinement was used. This experimental method is shown to be repeatable and can be performed with little required material (about 2 g). The data obtained could be useful to model development and validation, as well as quantifying detonability of materials.